A new species of the genus Lasioseius (Acari: Blattisociidae) inhabiting litter of secondary rainforest in Sumatra, Indonesia

A new species of blattisociid mites Lasioseius orangrimbae n. sp., that belongs to the floridensis-group, is described based on females and males from litter and soil samples of secondary rainforest in Sumatra, Indonesia.


Introduction
Currently, the mite family Blattisociidae (Mesostigmata: Ascoidea) comprises 14 globally distributed genera with Lasioseius Berlese 1916 as the most diverse and rich genus. Lasioseius includes a total of 206 described species that have been found in different habitats such as soil, grass, moss and litter, but also associated with insects and on plants (Moraes et al. 2016). Some species have been widely studied as potential biological control agents (Moraes et al. 2015).
The main goal of this paper is to describe one new species of the genus Lasioseius (Lasioseius) based on adult specimens (female and male) collected from litter of secondary rainforest in Bukit Duabelas National Park, Jambi Province, Sumatra, Indonesia.

Materials and methods
This study forms part of a large project investigating arthropods of Indonesia, within the framework of the interdisciplinary project "Ecological and socioeconomic functions of tropical lowland rainforest transformation systems (Sumatra, Indonesia)" -EFForTS. For more details on the study region and the experimental design see Drescher et al. (2016).
Mites were extracted from soil samples of 16 x 16 cm taken from the core plots of the project with a spade in the Bukit Duabelas National Park, Jambi Province, Sumatra (for exact localities and habitats see "Material examined" section). Litter and topsoil to a depth of 5 cm were extracted separately using the high gradient canister method described by Kempson et al. (1963). All specimens were collected in November 2013 by B. Klarner. Mites were initially stored in 70% ethanol, then cleared in 55% lactic acid, in some cases gnathosoma was dissected from idiosoma, and slide preparations were done with Hoyer's medium.
Photographs and measurements were made using a Nikon Eclipse Ci microscope equipped with phase contrast and connected to a digital camera (Nikon, High-definition Color Camera Head DS-Fi2) controlled by (Nikon, Camera Control Sight DS-L3). Most images were taken in stacks with the focal depth controlled manually. Selected images were combined using Zerene Stacker Version 1.04. In some cases, images captured from different regions of the body were combined using the 'photomerge' function in Adobe Photoshop, version 2015 (16.0 or 20150529.r.88; Adobe Systems Inc., San Jose, USA). Digital drawings were prepared with Adobe Illustrator, version CC 2015 (19.0.0), based on mite photographs.
All measurements are given in micrometers (μm) and included in the descriptions as a range (minimum-maximum). Lengths of shields were measured along their midlines; the level in which widths were measured are indicated in brackets. Leg measurements were taken from the proximal margin of the coxa, along of the midline of each segment, to the tip of the claw. Notations of body structures and idiosomal chaetotaxy generally follow Lindquist and Evans (1965). Leg chaetotaxy follows Evans (1963) and Evans and Till (1965). Notations for pore-like structures (gland pores and poroids/lyrifissures) follow the system of Athias-Henriot (1971) for ventral idiosoma and peritrematal shield, and Athias-Henriot (1975) for the dorsal idiosoma.
Based on the key to the world genera and subgenera of Blattisociidae (Moraza and Linquist 2011) and on the diagnosis provided by Moraza and Lindquist (2018) for the species-groups, the species described here forms part of the subgenus Lasioseius (Lasioseius) and the floridensisgroup by the combination of the following characters: females with most of the dorsal shield setae tricarinate and moderately long, many of them nearly as long as longitudinal intervals between their bases; posthumeral seta r4 short and simple, similar to r2, and at most half as long as neighboring tricarinate seta s4; tarsus II with one midlateral seta pl2 elongated and reaching nearly to base of pretarsus; leg IV with no tarsal setae longer than tibial segment; podonotal region of female dorsal shield with 21 pairs of setae, including r4 but excluding r5; and sternal shield with an anteromedial patch of reticula. The floridensis-group currently includes L. floridensis Berlese 1916, L. queenslandicus (Womersley, 1956), L. sugawarai (Ehara, 1964), and L. latinoamericanus Mineiro et al., 2009. Blattisociidae Lasioseius Berlese Lasiosieus Berlese 1916: 33;Lindquist and Evans 1965: 40;Christian and Karg 2006: 105;Lindquist and Moraza 2010: 4. Lasioseius orangrimbae n. sp. Quintero-Gutiérrez and Sandmann Figures 1-9, 10a Diagnosis Female -Dorsal shield with reticulate surface, bearing 36 pairs of setae that are relatively long and tricarinate, except z1, s1, r2, r4, J5 which are smooth and aciculate, Z3-Z5, S4 and S5 tricarinate and with serrate margin. Soft integument bearing only seven relatively short pairs of setae r5, r6, R2-6; seta R1 and UR series absents. Ventral shields with all setae aciculate and smooth, sternal shield mostly smooth, central region slightly punctate, sparse lateral striations, and with two parallel anteromedian lines between st1 and st2; st1 in the sternal shield. Genital shield punctate (difficult to discern) with posterior margin truncate; four transversely aligned and elongated platelets between genital and ventrianal shield. Ventrianal shield strongly reticulate, bearing six pairs of preanal setae ZV2-ZV3, JV1-JV3, JV4 10-11; posterior margin slightly narrow at level of JV4. Only three pairs of setae ZV1, ZV4 and JV5 on opisthogastric integument, JV5 at least twice longer than ZV1 and ZV4. Two pairs of semi-rounded metapodal elements. Spermatheca with a short major duct leading to a weakly sclerotized shallowly funnel-shaped calyx as long as wide from which a long and thin minor duct arise. Tarsus II with pl2 macrosetae.
Gnathosoma - (Figures 4a-c). Subcapitulum (Figure 4a) corniculi well sclerotized, elongated and horn-like. Internal malae lanceolate, densely fimbriated, with apices slightly beyond of the corniculi. Deutosternum with eight transverse rows of denticles with first row (most distal), from second to seventh rows with 10-15 denticles, the first seven lines are connected by the lateral subparallel deutosternal lines, eighth line (most proximal) extending beyond lateral deutosternal lines and with 20-23 denticles; with smooth lines laterad of delineating deutosternal lines at region between fifth and sixth transverse lines; subcapitular setae smooth and aciculate, h1 and h3 32 longer than h2 23 and pc 29. Chelicerae (Figure 4b). Fixed digit with 13 small teeth plus one distal hook-like tooth, and a setiform pilus dentilus; dorsal and antiaxial lyrifissures as well as dorsal setae distinct; mobile digit with three large teeth and one large distal tooth. Gnathotectum ( Figure. 4c) with three anterior projections, two serrate lateral projections and one acuminate middle process longer than the lateral ones (not serrate).
Spermathecal apparatus - (Figure 6). With a short major duct leading to a weakly sclerotized shallowly funnel-shaped calyx as long as wide from which a long 33 and thin minor duct arise with terminus duct indiscernible in specimens at hand.
Gnathosoma - (Figures 9a-b). As in female except the following: Chelicerae ( Figure  9a); fixed digit with 12 small teeth plus one distally hook-like tooth and a setiform pilus dentilus; dorsal and antiaxial lyrifissures and dorsal setae distinct; mobile digit with a single tooth slightly directed forward and distally hook-like; with a slightly curved spermadactyl. Gnathotectum (Figure 9b) anteromedian region of epistome convex, with variably denticulate extensions.
Legs -Similar to those of female. . Tarsus II with pl2 macrosetae.

Etymology
The epithet orangrimbae refers to forest-dwelling people "Orang Rimba" living in the sampling region.
Remarks Differential characters: Lasioseius orangrimbae n. sp., significantly differs from the other species in the floridensis-group by the smaller body size in females and males (Females n. sp., has a sclerotized, funnel-shaped calyx that is as long as wide without conspicuous vesicle, in L. floridensis the spermathecal apparatus is sclerotized, shallowly funnel-shaped calyx with a conspicuous vesicle and a long, relatively thick minor duct; in L. latinoamericanus the spermathecal apparatus has a densely sclerotized region (embolus) with a slender funnelshaped calyx with a conspicuous long vesicle and a very thin minor duct; in L. sugawarai the spermathecal apparatus is small, weakly sclerotized, bulbous and without discernible minor duct, and in L. queenslandicus the spermathecal apparatus is bifurcated after leaving the solenostome with a weakly sclerotized, tubular calyx and a relatively short thick minor. Also, females of L. orangrimbae n. sp. differ from the those of the other species in the floridensis-group in having a total of seven pairs of marginal setae on soft cuticle (r5-6, R2-6) with R1 and UR setae absent, while L. floridensis, L. latinoamericanus and L. queenslandicus have eight pairs of marginal setae (r5-6, R1-6) with setae UR present, and L. sugawarai has eleven pairs of marginal setae (r5-6, R1-7) with two pair of UR setae. In addition, females L. orangrimbae n. sp., have only three pairs of setae in the opisthogastric cuticle (JV5, ZV1, ZV4), compared to L. floridensis and L. latinoamericanus which have six pairs  and (ZV1,, respectively; L. latinoamericanus has seven pairs (ZV1, ZV3-ZV5, JV4-JV5, and a pair of submarginal UR) and L. sugawarai has five pairs (JV4-5, ZV1, ZV3-4). Finally, males of L. orangrimbae n. sp., do not have marginal setae (except r6 in one of the three examined males), whereas males in L. floridensis have five pairs of marginal setae (R2-6), L. queenslandicus two pairs (R2, R5) and L. latinoamericanus six pairs (R1-6).

Discussion
Five species of Lasioseius have been previously described from Sumatra L. sublaevis L. alter, L. frontalis, L. polydesmophilus and L. angustus. For L. sublaevis it is not possible to compare or stablish the subgenus or species group because the description is very short. Additionally, Christian and Karg (2006) did not include this species in their study. Lasioseius alter, L. frontalis, and L. polydesmophilus are not closely related to L. orangrimbae n. sp., because they belong to the subgenus Lasioseius (Endopodalius) Christian and Karg, 2006. Finally, L. angustus was described based only on males and also seems to belong to the subgenus Lasioseius (Endopodalius).
When examining our specimens with the key to the species of Lasioseius provided by Christian and Karg (2006) we ended in a similar way as reported in Britto et al. (2011). These authors reported that when they determined their specimens of L. floridensis with this key, it led them to the subgenus Crinidens, then to key 6 for their ometes-complex having five pairs  of setae on the ventrianal shield. In our case ending in the subgenus Crinidens for having most dorsal setae tricarinate, then to the Lasioseius-ometisimilis-complex key 5 for having 6 setae on the ventrianal shield, and at the end to the cuplet 21-22 to the species L. laciniatus Karg, 2006, andL. tricuspidis Christian andKarg, 2006 for having the following characters: a normal number of dorsal setae (not reduced), two pairs of metapodal plates, margins of the tectum with three clear "branches" with medial "branch" as long as the lateral ones which have serrations, most of the dorsal setae tricarinate and dorsal setae not as long to reach the base of the next setae, sternal seta st1 on the sternal shield, ventrianal shield slightly wider than longer, post anal seta not long. However, the tectum shape in L. laciniatus and L. tricuspidis do not resemble the one of L. orangrimbae n. sp., in L. orangrimbae n. sp. the lateral processes of the tectum are serrate with the middle process longer than the lateral ones, whereas in L. laciniatus the lateral processes of the tectum are serrate with the middle one shorter than the lateral ones, and in L. tricuspidis the lateral processes are three-pronged with the middle one little longer than the lateral ones. Additionally, L. orangrimbae has a well-developed anteromedial patch in the sternal shield, which is absent in L. laciniatus and L. tricuspidis.
Finally, we would like to emphasize that L. orangrimbae n. sp., fits well the characters stated in Moraza and Lindquist (2018: 68, entry 4) for the floridensis-group "Dorsal shield with post-humeral seta r4 short, simple, similar to r2, and not more than half as long as tricarinate seta s4 neighboring it medially; most dorsal setae tricarinate and moderately long, nearly as long as longitudinal intervals between their bases; anterior pair of sternal setae on weakly sclerotized presternal area, just before anterior margin of sternal shield; sternal shield with anteromedial patch of reticula; tarsus II with one midlateral seta pl2 elongated and reaching nearly to base of pretarsus", except the character "anterior pair of sternal setae on weakly sclerotized presternal area". However, when we compared our specimens with the key to the species of Lasioseius in Christian and Karg (2006), we noticed that some species in the subgenus Lasioseius (Crinidens) sensu Christian and Karg, 2006 especially the species in the part of the key 5 (Lasioseius-ometisimilis-complex) number 11(14) that states "The first pair of sternal setae localized anteriorly to the shield" may fall in the floridensis-group because they all fit the characters of the group but some of them do not have the "sternal shield with anteromedial patch of reticula", and it is not clear if all species of Lasioseius-ometisimiliscomplex also have "tarsus II with one midlateral seta pl2 elongated and reaching nearly to base of pretarsus". Examining holotype images of L. laciniatus and L. tricuspidis in VIRMISCO (Decker et al. 2018), we noticed that L. laciniatus and L. tricuspidis have the macroseta pl2 in tarsus II (Figures 10b-c). Therefore, it is not clear why the floridensisgroup does not include species of the subgenus Lasioseius (Crinidens) sensu Christian and Karg (2006), or where those species would fall under the species-group key presented in Moraza and Lindquist (2018).
All the previous suggests that the subgenus Lasioseius (Crinidens) sensu Christian and Karg (2006) needs to be revised considering if certain species may belong to the floridensis-group, or if with a slight shift of characters the floridensis-group may be split or expanded to include other species.